电源管理

If you are in a local user session and no other session is active, the following commands will work without root privileges. If not, systemd will automatically ask you for the root password.

Shut down and reboot the system:

$ systemctl reboot

Shut down and power-off the system:

$ systemctl poweroff

Shut down and halt the system:

$ systemctl halt

Suspend the system:

$ systemctl suspend

Hibernate the system:

$ systemctl hibernate

启动级别（runlevel）/目标（target）

Runlevels is a legacy concept in systemd. Systemd uses targets which serve a similar purpose as runlevels but act a little different. Each target is named instead of numbered and is intended to serve a specific purpose with the possibility of having multiple ones active at the same time. Some targets are implemented by inheriting all of the services of another target and adding additional services to it. There are systemd targets that mimic the common SystemVinit runlevels so you can still switch targets using the familiar telinit RUNLEVEL command.

获取当前启动级别/目标

The following should be used under systemd instead of runlevel:

# systemctl list-units --type=target

创建新目标

The runlevels that are assigned a specific purpose on vanilla Fedora installs; 0, 1, 3, 5, and 6; have a 1:1 mapping with a specific systemd target. Unfortunately, there is no good way to do the same for the user-defined runlevels like 2 and 4. If you make use of those it is suggested that you make a new named systemd target as /etc/systemd/system/<your target> that takes one of the existing runlevels as a base (you can look at /usr/lib/systemd/system/graphical.target as an example), make a directory /etc/systemd/system/<your target>.wants, and then symlink the additional services from /usr/lib/systemd/system/ that you wish to enable.

目标表

SysV Runlevel

Systemd Target

Notes

0

runlevel0.target, poweroff.target

Halt the system.

1, s, single

runlevel1.target, rescue.target

Single user mode.

2, 4

runlevel2.target, runlevel4.target, multi-user.target

User-defined/Site-specific runlevels. By default, identical to 3.

3

runlevel3.target, multi-user.target

Multi-user, non-graphical. Users can usually login via multiple consoles or via the network.

5

runlevel5.target, graphical.target

Multi-user, graphical. Usually has all the services of runlevel 3 plus a graphical login.

6

runlevel6.target, reboot.target

Reboot

emergency

emergency.target

Emergency shell

切换启动级别/目标

In systemd runlevels are exposed via "target units". You can change them like this:

# systemctl isolate graphical.target

This will only change the current runlevel, and has no effect on the next boot.

修改默认启动级别/目标

The standard target is default.target, which is aliased by default to graphical.target (which roughly corresponds to the old runlevel 5). To change the default target at boot-time, append one of the following kernel parameters to your bootloader:

systemd.unit=multi-user.target (which roughly corresponds to the old runlevel 3),

systemd.unit=rescue.target (which roughly corresponds to the old runlevel 1).

Alternatively, you may leave the bootloader alone and change default.target. This can be done using systemctl:

# systemctl enable multi-user.target

The effect of this command is outputted by systemctl; a symlink to the new default target is made at /etc/systemd/system/default.target. This works if, and only if:

[Install]
Alias=default.target

is in the target's configuration file. Currently, multi-user.target and graphical.target both have it.

Simply delete the symlink and systemd will use its stock default.target (i.e. graphical.target).

# rm /etc/systemd/system/default.target

If /etc/locale.conf is used for setting the locale, add an entry to /etc/environment:

/etc/environment

LANG=en_US.utf8

使用服务文件

Note: Using this method there will be no PAM session created for your user. Therefore ConsoleKit (which gives you access to shutdown/reboot, audio devices etc.) will not work properly. For the recommended way, see: Automatic_login_to_virtual_console#With_systemd.

If you are only looking for a simple way to start X directly without a display manager, you can create a service file similar to this:

systemd 日志

By default, running a syslog daemon is no longer required. To read the log, use:

# journalctl

The journal writes to /run/systemd/journal, meaning logs will poof on reboot. For non-volatile logs, create /var/log/journal/:

# mkdir /var/log/journal/

日志大小限制

If the journal is made non-volatile, its size limit is set to a default value of 10% of the size of the respective file system. E.g. with /var/log/journal located on a 50GiB root partition this would lead to 5GiB of journal data. The maximum size of the persistent journal can be controlled by SystemMaxUse in /etc/systemd/journald.conf, so to limit it for example to 50MiB uncomment and edit the corresponding line to:

SystemMaxUse=50M

Look at man journald.conf for more info.

配合传统日志服务

Compatibility with classic syslog implementations is provided via a
socket /run/systemd/journal/syslog, to which all messages are forwarded.
To make the syslog daemon work with the journal, it has to bind to this socket instead of /dev/log (official announcement). For syslog-ng change /etc/syslog-ng/syslog-ng.conf source section to:

By default, journald is configured to read from /proc/kmsg, but this will collide with a syslog implementation doing the same (systemd-devel post). Disable reading /proc/kmsg by systemd-journald in /etc/systemd/journald.conf:

ImportKernel=no

网络

DHCP 动态获取 IP

If you simply want to use DHCP for your ethernet connection, you can use dhcpcd@.service from the systemd-arch-units package.
To enable DHCP for eth0, simply use:

# systemctl start dhcpcd@eth0.service

You can enable the service to automatically start at boot with:

# systemctl enable dhcpcd@.service

Note that this will enable the service for eth0 by default. If you want to use another interface, you have to create the symlink manually, e.g.:

其他配置方式

For static, wireless or advanced network configuration like bridging you can use netcfg or NetworkManager which both provide systemd service files.

If you need a static ethernet configuration, but don't want to use netcfg, there is a custom service file available on the Systemd/Services page.

Arch 整合

Integration with Arch's classic configuration is accomplished via the initscripts-systemd package. This is an optional package containing unit files and scripts needed to emulate Arch's initscripts, which can be used to ease the transition from sysVinit to systemd.

/etc/inittab is not used at all.

/etc/rc.local and /etc/rc.local.shutdown can be run at startup and shutdown by enabling rc-local.service and rc-local-shutdown.service.

Warning: Usage of this package is not recommended. In particular, arch-load-modules.service and arch-daemons.target are unsupported as a long-term solution and will be removed in the future. When ever possible, use native systemd configuration files instead.

Most people will not need all (if any) of these units, and they can be easily disabled with:

# systemctl disable <unitfile>

The plan is to remove most of the functionality from this package as soon as it is handled elsewhere (mostly in udev/systemd/kernel).

rc.conf

Some variables in /etc/rc.conf are respected by this glue work. For a pure systemd setup it is recommended to use the native systemd configuration files which will take precedence over /etc/rc.conf.

Supported variables:

LOCALE

KEYMAP

CONSOLEFONT

CONSOLEMAP

HOSTNAME

MODULES

DAEMONS: Ordering and blacklisting is respected, if a native systemd service file by the same name as a daemon exists, it will take precedence, this logic can be disabled by systemctl disable arch-daemons.target

rc-local.service / rc-local-shutdown.service

arch-daemons.target

Parses the DAEMONS array in /etc/rc.conf and starts the services. If a native systemd unit exists (by the same name) for a given daemon, this is used; otherwise, the script in /etc/rc.d/ is used to control the unit.

FAQ

优化

systemd-analyze

Systemd provides a tool called systemd-analyze that allows you to analyze your boot process so you can see which unit files are causing your boot process to slow down. You can then optimize your system accordingly. You have to install python2-dbus to use it.

To see how much time was spent in kernel-/userspace on boot, simply use:

systemd-analyze

Tip: If you add the timestamp hook to your HOOKS array in /etc/mkinitcpio.conf and rebuild your initramfs, systemd-analyze will also be able to show you how much time was spent in the intramfs.

To list the started unit files, sorted by the time each of them took to start up:

systemd-analyze blame

You can also create a SVG file which describes your boot process grapically, similiar to Bootchart:

systemd-analyze plot > plot.svg

使用 bootchart

You can use a version of bootchart to visualize the boot sequence.
Since you are not able to put a second init into the kernel cmdline you won't be able to use any of the standard bootchart setups. However the bootchart2AUR package from AUR comes with an undocumented systemd service. After you've installed bootchart2 do:

shell 短命令

Systemd daemon management requires a bit more text entry to accomplish tasks such as start, stopped, enabling, checking status, etc. The following functions can be added one's ~/.bashrc to help streamline interactions with systemd and to improve the overall experience.

精简输出信息

Change verbose to quiet on the kernel line in GRUB. For some systems, particularly those with an SSD, the slow performance of the TTY is actually a bottleneck, and so less output means faster booting.

Early start

One central feature of systemd is dbus and socket activation, this causes services to be started when they are first accessed, and is generally a good thing. However, if you know that a service (like console-kit) will always be started during boot, then the overall boot time might be reduced by starting it as early as possible. This can be achieved (if the service file is set up for it, which in most cases it is) by issuing:

# systemctl enable console-kit-daemon.service

This will cause systemd to start console-kit as soon as possible, without causing races with the socket or dbus activation.

自动挂载（automount）

The default setup will fsck and mount all filesystems before starting most daemons and services. If you have a large /home partition, it might be better to allow services that do not depend on /home to start while /home is being fsck'ed. This can be achieved by adding the following options to the fstab entry of your /home partition:

noauto,x-systemd.automount

This will fsck and mount /home when it is first accessed, and the kernel will buffer all file access to /home until it is ready.

If you have encrypted filesystems with keyfiles, you can also add the noauto parameter to the corresponding entries in /etc/crypttab. systemd will then not open the encrypted device on boot, but instead wait until it is actually accessed and then automatically open it with the specified keyfile before mounting it. This might save a few seconds on boot if you are using an encrypted RAID device for example, because systemd doesn't have to wait for the device to become available. For example:

/etc/crypttab

data /dev/md0 /root/key noauto

Readahead

systemd comes with its own readahead implementation, this should in principle improve boot time. However, depending on your kernel version and the type of your hard drive, your mileage may vary (i.e. it might be slower). To enable, do:

Further, you can replace ConsoleKit's functionality with systemd. To do this, polkit needs to be rebuilt from ABS with systemd enabled (--enable-systemd), and stuff like USB automounting will work without consolekit. DBus supports systemd since version 1.6.0, so there's no longer need to build it from Git.

Troubleshooting

Shutdown/Reboot takes terribly long

If the shutdown process takes a very long time (or seems to freeze) most likely a service not exiting is to blame. systemd waits some time for each service to exit before trying to kill it.
To find out if you are affected see this article in the fedora wiki.

SLiM and xfce-session

One setup that can produce a shutdown freeze is Xfce in conjunction with SLiM: Shutting down/rebooting using xfce-session will cause slim.service to hang for half a minute until systemd kills it the hard way.
One workaround is to create a modified slim.service: